DEM extends forecasts for Local Air Quality Advisory in Marion County

MARION COUNTY – The Indiana Department of Environmental Management (IDEM) is forecasting a:Local Air Quality Advisory (LAQA) for Indianapolis (Marion County) beginning at 6 p.m. ET on Wednesday, Oct. 28 through 10 a.m. ET on Thursday, Oct. 29Hourly fine particulate matter (PM_2.5) levels are forecast to reach the Unhealthy for Sensitive Groups (Orange) range due to stagnant weather conditions. Air quality monitoring and expected weather patterns indicate PM_2.5 may rise to very high levels during this period. Conditions are expected to improve near the end of the advisory window, though elevated PM_2.5 could continue into the following day.

Detailed Analysis
Overnight hourly PM_2.5 readings at the Washington Park, West 18th St and I-70 monitors early Wednesday were well above the daily National Ambient Air Quality Standards (35.5 micrograms per cubic meter). PM_2.5 concentrations are anticipated to remain in the high moderate AQI range during the day. Calm winds and a shallow mixing layer forecasted for Wednesday night into Thursday morning are again expected to increase PM_2.5 levels overnight. Elevated PM_2.5 values may persist into the day on Thursday, with conditions improving later in the afternoon as wind speeds pick up.

Local Air Quality Advisory (LAQA) Description 
A LAQA is similar to an Air Quality Action Day (AQAD). IDEM will forecast an LAQA when the overall daily average PM_2.5 concentrations may not warrant an AQAD over the course of a 24-hour period, but hourly values may reach levels in the Unhealthy for Sensitive Groups (Orange) Air Quality Index (AQI) range or higher for several hours.

For more information, please read IDEM’s Local Air Quality Advisory fact sheet.

SmogWatch.IN.gov
Visit SmogWatch.IN.gov to:View air quality information for all Indiana counties; Learn more about Air Quality Action Days, Local Air Quality Advisories and recommended actions for both alerts; Learn more about ozone and fine particulate matter; and Sign up for air quality alerts.

Note: IDEM forecasts are based, solely or in part, on data from air quality monitors located throughout the state. Air quality information for all Indiana counties can be found at SmogWatch.IN.gov.